The Tissue and Pathology core B is directed by breast pathologist, Dr. Andrea Richardson. This shared resource core will provide fresh human breast tumor samples of each of the ER and HER2 immunophenotypes for generation of early passage transplantable human-in-mouse xenografts in collaboration with Dr. Brown. The tissue and pathology core will characterize the xenograft tumors and compare to the paired original human tumor for histomorphology, immunophenotype, and molecular (gene expression and mutation) profiling. These xenograft models will be used for studies proposed in projects 1, 2, 4 and 6. The core will provide fresh breast tissue from women without cancer (breast reductions) and from women with germline BRCA1 or BRCA2 mutation for isolation of epithelial progenitor cells for studies proposed in projects 2 and 5. The tissues collected are from women who provided informed consent to one of our research banking protocols that allows for collection of excess tissues from clinical specimens for research and for collection of and linkage to long term outcome data. In addition, the core will provide research pathology services to perform histopathology analysis of mouse tumor models in projects 3 and 4.